Towards fundamental understanding of the accumulation, chemistry, and human exposure to indoor surface-associated wildfire smoke constituents

Portland State University, Portland OR

Investigators

Abstract

When wildfire smoke enters buildings, particles and chemicals can stick to indoor surfaces like floors and clothing, remaining indoors even after the smoke outside clears. The health risks from these contaminated surfaces are largely unknown, presenting a potential hidden danger in homes and workplaces. This project will study how smoke pollutants accumulate on common indoor materials, how these chemicals might change over time into new, possibly more toxic substances, and how people might be exposed to them through re-emission and contact with contaminated items. Understanding the interactions of smoke and indoor materials is essential for estimating the risks of smoke-exposed indoor surfaces. This work will contribute to safeguarding public health as it will improve understanding of these often-overlooked post-wildfire exposure risks indoors, help inform public health guidance and air quality policies and train the next generation of scientists to tackle this growing national environmental health challenge. This project seeks to establish fundamental understanding of the accumulation, chemistry, and subsequent human exposure risks from wildfire smoke constituents on indoor surfaces, a critical and scientifically unaddressed pathway. The project goals are threefold: first, to quantify the accumulation and post-event emission dynamics of organic compounds by determining mass-transfer and partitioning coefficients for smoke on authentic indoor materials; second, to elucidate the chemical transformations of surface-bound polycyclic aromatic hydrocarbons (PAHs) into potentially more toxic byproducts like quinones and nitro-PAHs under various indoor lighting and oxidant conditions; and third, to develop mechanistic models that quantify post-smoke event human exposure via inhalation and dermal pathways. To achieve these goals, a combination of experiments in a large environmental chamber and advanced analytical methods—including real-time proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) alongside GC-MS, LC-MS, and DART-MS—will be utilized to parameterize surface interactions and identify chemical byproducts formed through lighting and oxidant conditions relevant to indoor spaces. Results of experiments will be used to develop predictive exposure models, including estimation of inhalation exposure by resuspension/partitioning and development of a 1-D skin uptake model for dermal exposure to long-lasting indoor smoke constituents that may be encountered through contact with clothing. Together, the experiments will enable models of pollutant dynamics that represent a significant contribution to fundamental understanding of wildfire smoke constituent exposure by providing a mechanistic framework to assess the health risks from smoke-exposed indoor materials. Outcomes of this work will be shared through dissemination with regional policymakers, the public, and academic and industry conferences, thereby informing future public health guidance and building science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.